If acupuncture is able to prevent hypertrophy of the heart, it could therefore prevent the heart from overloading and thus prevent heart failure or sudden death. We therefore studied the effects of acupuncture on blood pressure and cardiac muscle cells. Rats with spontaneous hypertension were divided into three acupuncture treatment groups and one non-treatment group. The treatment groups were classified as sham acupoint, Yanglingquan (GB. 34) and Quchi (LI. 11) groups. The measurements recorded included changes in tail pressure, femoral arterial pressure, left ventricular weight (LVW), whole heart weight (WHW), body weight (BW), LVW/BW and WHW/BW ratios and the size of the cardiac muscle cells. The results showed that femoral arterial pressure of subjects which were needled on the selected points for 3 days dropped. Acupuncture at these two acupoints seemed to improve the condition of hypertension in a short period of time. Significant changes in the femoral arterial pressure were observed in all subjects when they were treated for 6 days. In the two acupoint groups, the LVW/BW and the WHW/BW ratios did not change significantly. Cardiac muscle cells reduced in size in the Yanglingquan (GB. 34) treatment groups. This indicates that the Yanglingquan (GB. 34) points not only can lower blood pressure, but also prevent hypertrophy of cardiac muscle cells in spontaneous hypertensive rats (SHR). Therefore, acupuncture could be a good treatment modality for hypertension and hypertrophy of the heart.